N = int(input())
A = list(input().split())

B = []
for a in A:
    if a == '+':
        b = B.pop()
        a = B.pop()
        B += [a+b]
    elif a == '-':
        b = B.pop()
        a = B.pop()
        B += [a-b]
    else:
        B += [int(a)]

print(*B)